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Biomedical subjects

M Samara

Publications and source records attributed to M Samara.

17 recordsLinked to original sources
PubMed2004

Influence of mixing method on the cement temperature-mixing time history and doughing time of three acrylic cements for vertebroplasty.

Acrylic cements are increasingly being used to augment osteoporotic vertebrae in a procedure called vertebroplasty. Two significant factors that may complicate the use of acrylic cements are: (a) short handling time, which may result in insufficient filling of the vertebra; and (b) exothermic setting (curing) behavior, which may result in thermal damage of the surrounding tissue. It has been previously reported that mixing the cement components under oscillation, as compared to manual mixing, increases the handling time. More specifically, it seems that oscillatory mixing slows down the cement polymerization process and, consequently, widens the time window during which cement is injectable. However, the effect of oscillatory mixing on the exothermic setting behavior of cement undergoing polymerization has not been examined. In this study, the exothermic setting behavior of three commercially available acrylic cements--Antibiotic Simplex, DP-Pour&trade, and Vertebroplastic--were examined for both manual and oscillatory mixing methods. For each combination of cement and mixing method, the parameters that were measured were the exothermic setting curve (and hence the cement setting temperature and setting time) and the cement doughing time. It was found that oscillatory mixing had no significant effect on any of these parameters. Based on the results of this study, it can be concluded that, for the tested cements, the setting process is a reaction-controlled process rather than a diffusion-controlled one. Clinically, this implies that oscillatory mixing may be used to increase the working period for acrylic cements without increasing the risk of thermal damage to surrounding tissue.

Bone Substitutes↗
PubMed2004

Influence of oscillatory mixing on the injectability of three acrylic and two calcium-phosphate bone cements for vertebroplasty.

Injecting acrylic and, increasingly, calcium-phosphate cements into the porous bone structure is an emerging procedure, referred to as vertebroplasty, for the augmentation of osteoporotic vertebrae. Despite the benefits of vertebroplasty, it has limitations. The limitations of interest in this study are the injectability of bone cements and their mixing variability (i.e., low reproducibility of resulting viscosity). The objective of this study is to investigate the effect of oscillatory versus manual mixing on cement viscosity and mixing variability. Five cements are tested: (a) Vertebroplastic, (b) DP-Pour, (c) Antibiotic Simplex, (d) chronOS Inject, and (e) Biopex. Compared to manual mixing, oscillatory mixing significantly decreased the mean viscosity and the mixing variability, which was inferred from the coefficient of variation. For example, under oscillatory mixing, the viscosity and the variability for Vertebroplastic decreased to one-third of the corresponding values for manual mixing. Similar results were obtained for the other cements. The decrease in viscosity is attributed to the pseudo-plastic behavior of bone cements. The decrease in the variability of cement viscosity was attributed to greater dispersive mixing of the cement components under oscillatory mixing. The decrease in viscosity eases the injection by reducing the pressure required. The decrease in the variability of cement viscosity increases reproducibility of the cement injection. Oscillatory mixing appears to have the potential to contribute to improving vertebroplasty.

Bone Substitutes↗
PubMed1994

Purification and characterization of an acetyl esterase from Aspergillus niger.

Optimized acetyl esterase enzyme production conditions using Aspergillus niger ATCC 10864 in 14-L fermentation jars were determined to be 33 degrees C, 1.5 vvm aeration, and 300 rpm agitation without pH control. The acetyl esterase was purified by precipitation in 60-80% saturation in ammonium sulfate. The pellet was applied directly to a Pharmacia high-load Phenyl Sepharose column for hydrophobic interaction chromatography and purified to homogeneity in two steps. Stability and kinetic characteristics of the acetyl esterase were determined over a pH range of 4.0-7.5 and from 4 to 45 degrees C. At temperatures > 25 degrees C, stability was superior at pH values < 5.0. The temperature activity optimum was 35 degrees C, and the pH optimum was 7.0. The Vmax was determined to be 46,700 U/mg protein, and the Km was 0.023M p-nitrophenyl acetate at pH 6.5 in 0.2M phosphate buffer at 35 degrees C. The mol wt of the enzyme was 35,000 dalton by size-exclusion chromatography and SDS gel electrophoresis. The N-terminal amino acid sequence and the glycosylation composition were also determined.

Acetylesterase↗
PubMed1988

Concurrent collagenous colitis and multiple ileal carcinoids.

A case of collagenous colitis in a patient with ileal carcinoid is described. Considerable fibrofatty thickening of the small bowel mesentery was present. The association of these findings appears to be unprecedented. Further observations are required to ascertain that collagenous colitis is one of the protean manifestations of carcinoid tumor.

Carcinoid Tumor↗
PubMed1987

Breast carcinoma metastatic to the nasopharynx.

A case report of a patient with adenocarcinoma of the breast with metastasis to the nasopharynx is described. The patient presented initially with pulmonary metastasis followed later by metastasis to the left jugulo-digastric lymph nodes. A prominent but asymptomatic nasopharyngeal mass was concomitantly discovered on head and neck examination. Three months later, symptoms of panhypopituitarism developed. Invasion of the base of the skull and pituitary were documented. Patients with adenocarcinoma of the breast and high cervical node metastasis should have a thorough otolaryngologic and head and neck evaluation. Metastatic carcinoma to the nasopharynx is an extremely rare occurrence. Only two cases of bronchogenic carcinoma of the lung and two cases of hypernephroma metastatic to the nasopharynx have been reported in the literature (Bernstein et al., 1966). We present what we believe to be the first case of metastatic adenocarcinoma of the breast to the nasopharynx.

Adenocarcinoma↗
PubMed1987

Primary lymphoma in the salivary glands: report of five cases and review of the literature.

The finding of a lymphoma in a major salivary gland could mean one of two things: either it is part of a disseminated process, or it is the first clinicopathologic evidence of lymphoma. In the latter instance, whether the disease originated in the glandular stroma itself or in a paraglandular lymph node and then invaded the stroma, the lymphoma is defined as primary, as long as there is no detectable disease outside the salivary gland. Five cases of primary salivary gland lymphomas are described. All had a complete clinical staging including chest x-ray, bilateral bone marrow biopsy, liver-spleen scan, bilateral pedal lymphangiography and/or abdominal CT scan. There was no evidence of lymphoma outside the gland in any of the patients described; hence, these can be labeled as primary lymphomas of the salivary gland. Review of the literature suggests that this presentation of the disease is extremely rare. Although 324 cases of salivary gland lymphomas have been described in the literature, only six may be considered primary by our criteria. The remaining patients were either not adequately staged or had documented evidence of disease elsewhere at the time of diagnosis. The diagnosis of primary salivary gland lymphoma should not be made unless complete staging is performed.

Adenolymphoma↗
PubMed1984

Collagenous colitis. Report of a case.

A 50-year-old woman presented with a long history of nausea, abdominal pain, weight loss, and intermittent watery diarrhea. All investigations were negative except for the finding, on five separate colonoscopic biopsies, of a layer of band-like collagen beneath the surface epithelium, diagnostic of collagenous colitis.

Colitis↗
PubMed1981

Effect of anesthesia on maximal cochlear microphonics.

During prolonged periods of pentobarbital anesthesia (6-8 h), cochlear microphonics (CM) in cats became reduced by approximately 6 dB, but only in the region of maximal responses ("truncation"). For the following reasons, this change is held to be neurally mediated, specifically by an impairment of the olivocochlear bundle (OCB): (1) Its onset coincided with the disappearance of efferent action potentials, normally superimposed on low-frequency CM. (2) OCB stimulation augments CM by approximately 6 dB, once more only in the region of maximal responses [4]. (3) Sectioning of the OCB reduces maximal CM responses [8]. (4) Truncation was produced by two neural blocking agents, azide and DFP [10], most likely also resulting from OCB impairments. (5) At the high input levels required to produce maximal responses, CM ought to become slightly elevated by acoustically-evoked OCB activity. This elevation should cease to occur on impairment of OCB under the effect of pro-longed anesthesia; thus there would be an apparent truncation.

Anesthetics↗
PubMed1981

Collision tumor of the frontal sinus: evidence of prior intrasinus instillation of thorotrast.

Carcinoma of the frontal sinus is relatively rare. We describe a case of two independent carcinomas, squamous cell and adenoid cystic, in the right frontal sinus region of a patient who received sinus irrigation with an unidentified, substance 30 years previously. Radioautography performed on sections of the tumor tissue revealed linear tracks of the type produced by thorium decay, strongly suggesting that the substance was thorotrast. In addition to being the first description of a "collision tumor" of the frontal sinus, the case would represent the first reported instance of frontal sinus carcinoma following intrasinus instillation of thorotrast.

Aged↗
PubMedDate not supplied

Familial achalasia with absent tear production.

Three of five siblings were evaluated because of dysphagia and failure to thrive. Radiologic and manometric studies were consistent with achalasia of the cardia. All of these siblings had deficient tear production. This report documents the unusual association of familial achalasia and deficient tear production, which is probably an autosomal recessive inherited syndrome.

Child↗
PubMedDate not supplied

[Instrumental dilatation of esophageal and gastric stenoses using Gruntzig's catheter and Celestin's dilator. Preliminary results].

The aim of this study was to present the technique of endoscopic dilatation and the preliminary results obtained with 2 new instruments, the Grüntzig balloon catheter, and the Celestin dilator, in patients with esophageal or gastric strictures. The Grüntzig balloon catheter was used 11 times in 7 patients (6 adults and one child aged 1 1/2 year), for the dilatation of severe or irregular strictures of the esophagus (5 cases), the stomach (1 case) and the pylorus (1 case). Partial (4 cases) or complete relief (2) were observed and allowed subsequent use of the Celestin bougies (2 cases), or the introduction of an esophageal prosthesis (1 case). In the child with caustic stricture of the esophagus, dilatation with the Grüntzig balloon-catheter was complicated twice by perforation. In the second case, the perforation was related to the technique used in dilatation and was treated by conservation measures. Endoscopic dilatations with the Celestin bougies were performed in 27 patients with benign (including 9 peptic strictures) or malignant strictures (14 cases, 7 related to esophageal cancer, and 7 to cancer of the cardia). A total of 74 dilatations were performed, attaining a maximum diameter of 16 or 18 mm in one session, in 21 patients (78 p. 100 of the cases). In the case of peptic stricture, the anatomical result was excellent in 8 patients and the functional result good in 7 of 9 cases. In case of malignant stricture, the result was conditioned by the evolution of the tumor; recurrence of dysphagia called for either repeated dilatations (8 cases) or the introduction of an esophageal prosthesis (5 cases).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗